/*
  ==============================================================================

   This file is part of the juce_core module of the JUCE library.
   Copyright (c) 2015 - ROLI Ltd.

   Permission to use, copy, modify, and/or distribute this software for any purpose with
   or without fee is hereby granted, provided that the above copyright notice and this
   permission notice appear in all copies.

   THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD
   TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN
   NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
   DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
   IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
   CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

   ------------------------------------------------------------------------------

   NOTE! This permissive ISC license applies ONLY to files within the juce_core module!
   All other JUCE modules are covered by a dual GPL/commercial license, so if you are
   using any other modules, be sure to check that you also comply with their license.

   For more details, visit www.juce.com

  ==============================================================================
*/

class NamedPipe::Pimpl
{
public:
    Pimpl (const String& pipePath, bool createPipe)
       : pipeInName  (pipePath + "_in"),
         pipeOutName (pipePath + "_out"),
         pipeIn (-1), pipeOut (-1),
         createdFifoIn (false),
         createdFifoOut (false),
         createdPipe (createPipe),
         stopReadOperation (false)
    {
        signal (SIGPIPE, signalHandler);
        juce_siginterrupt (SIGPIPE, 1);
    }

    ~Pimpl()
    {
        if (pipeIn  != -1)  ::close (pipeIn);
        if (pipeOut != -1)  ::close (pipeOut);

        if (createdPipe)
        {
            if (createdFifoIn)  unlink (pipeInName.toUTF8());
            if (createdFifoOut) unlink (pipeOutName.toUTF8());
        }
    }

    int read (char* destBuffer, int maxBytesToRead, int timeOutMilliseconds)
    {
        const uint32 timeoutEnd = getTimeoutEnd (timeOutMilliseconds);

        if (pipeIn == -1)
        {
            pipeIn = openPipe (createdPipe ? pipeInName : pipeOutName, O_RDWR | O_NONBLOCK, timeoutEnd);

            if (pipeIn == -1)
                return -1;
        }

        int bytesRead = 0;

        while (bytesRead < maxBytesToRead)
        {
            const int bytesThisTime = maxBytesToRead - bytesRead;
            const int numRead = (int) ::read (pipeIn, destBuffer, (size_t) bytesThisTime);

            if (numRead <= 0)
            {
                if (errno != EWOULDBLOCK || stopReadOperation || hasExpired (timeoutEnd))
                    return -1;

                const int maxWaitingTime = 30;
                waitForInput (pipeIn, timeoutEnd == 0 ? maxWaitingTime
                                                      : jmin (maxWaitingTime,
                                                              (int) (timeoutEnd - Time::getMillisecondCounter())));
                continue;
            }

            bytesRead += numRead;
            destBuffer += numRead;
        }

        return bytesRead;
    }

    int write (const char* sourceBuffer, int numBytesToWrite, int timeOutMilliseconds)
    {
        const uint32 timeoutEnd = getTimeoutEnd (timeOutMilliseconds);

        if (pipeOut == -1)
        {
            pipeOut = openPipe (createdPipe ? pipeOutName : pipeInName, O_WRONLY, timeoutEnd);

            if (pipeOut == -1)
                return -1;
        }

        int bytesWritten = 0;

        while (bytesWritten < numBytesToWrite && ! hasExpired (timeoutEnd))
        {
            const int bytesThisTime = numBytesToWrite - bytesWritten;
            const int numWritten = (int) ::write (pipeOut, sourceBuffer, (size_t) bytesThisTime);

            if (numWritten <= 0)
                return -1;

            bytesWritten += numWritten;
            sourceBuffer += numWritten;
        }

        return bytesWritten;
    }

    static bool createFifo (const String& name, bool mustNotExist)
    {
        return mkfifo (name.toUTF8(), 0666) == 0 || ((! mustNotExist) && errno == EEXIST);
    }

    bool createFifos (bool mustNotExist)
    {
        createdFifoIn  = createFifo (pipeInName, mustNotExist);
        createdFifoOut = createFifo (pipeOutName, mustNotExist);

        return createdFifoIn && createdFifoOut;
    }

    const String pipeInName, pipeOutName;
    int pipeIn, pipeOut;
    bool createdFifoIn, createdFifoOut;

    const bool createdPipe;
    bool stopReadOperation;

private:
    static void signalHandler (int) {}

    static uint32 getTimeoutEnd (const int timeOutMilliseconds)
    {
        return timeOutMilliseconds >= 0 ? Time::getMillisecondCounter() + (uint32) timeOutMilliseconds : 0;
    }

    static bool hasExpired (const uint32 timeoutEnd)
    {
        return timeoutEnd != 0 && Time::getMillisecondCounter() >= timeoutEnd;
    }

    int openPipe (const String& name, int flags, const uint32 timeoutEnd)
    {
        for (;;)
        {
            const int p = ::open (name.toUTF8(), flags);

            if (p != -1 || hasExpired (timeoutEnd) || stopReadOperation)
                return p;

            Thread::sleep (2);
        }
    }

    static void waitForInput (const int handle, const int timeoutMsecs) noexcept
    {
        struct timeval timeout;
        timeout.tv_sec = timeoutMsecs / 1000;
        timeout.tv_usec = (timeoutMsecs % 1000) * 1000;

        fd_set rset;
        FD_ZERO (&rset);
        FD_SET (handle, &rset);

        select (handle + 1, &rset, nullptr, 0, &timeout);
    }

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (Pimpl)
};

void NamedPipe::close()
{
    if (pimpl != nullptr)
    {
        pimpl->stopReadOperation = true;

        char buffer[1] = { 0 };
        ssize_t done = ::write (pimpl->pipeIn, buffer, 1);
        (void) done;

        ScopedWriteLock sl (lock);
        pimpl = nullptr;
    }
}

bool NamedPipe::openInternal (const String& pipeName, const bool createPipe, bool mustNotExist)
{
   #if JUCE_IOS
    pimpl = new Pimpl (File::getSpecialLocation (File::tempDirectory)
                         .getChildFile (File::createLegalFileName (pipeName)).getFullPathName(), createPipe);
   #else
    String file (pipeName);

    if (! File::isAbsolutePath (file))
        file = "/tmp/" + File::createLegalFileName (file);

    pimpl = new Pimpl (file, createPipe);
   #endif

    if (createPipe && ! pimpl->createFifos (mustNotExist))
    {
        pimpl = nullptr;
        return false;
    }

    return true;
}

int NamedPipe::read (void* destBuffer, int maxBytesToRead, int timeOutMilliseconds)
{
    ScopedReadLock sl (lock);
    return pimpl != nullptr ? pimpl->read (static_cast <char*> (destBuffer), maxBytesToRead, timeOutMilliseconds) : -1;
}

int NamedPipe::write (const void* sourceBuffer, int numBytesToWrite, int timeOutMilliseconds)
{
    ScopedReadLock sl (lock);
    return pimpl != nullptr ? pimpl->write (static_cast <const char*> (sourceBuffer), numBytesToWrite, timeOutMilliseconds) : -1;
}
